Manufacture of shaped articles from acrylonitrile polymers by wet spinning



P 17, 1968 w. B. HENDERSON ETAL 3,402,235

MANUFACTURE OF SHAPED'ARTICLES FROM ACRYLONITRILE POLYMERS BY WETSPINNING Filed April 8, 1964 2 Sheets-Sheet 1 FIG. 1. FIG. 2.

FIG. 3. FIG. 4.

INVENTORS GE RD R. BAUR BY WILLIAM B. HENDERSON AT TOR NEY 3,402,235RILE Sept. 17, 1968 w. a. HENDERSON ETAL MANUFACTURE OF SHAPED ARTICLESFROM ACRYLONIT POLYMERS BY WET SPINNING 2 Sheets-Sheet 2 Filed April 8,1964 FIG. 6.

FIG. 5.

FIG.

FIG. 7.

INVENTORS GERD R. BAUR WILLIAM B. HENDERSON ATTORNEY United StatesPatent ABSTRACT OF THE DISCLOSURE The Wet spinning of acrylonitrilepolymer filaments by extruding a solution of polyacrylonitn'le into aspin bath which comprises at least 50 percent by weight of an amide ormixtures of amides having the formula on. H I

RCNR2 wherein R is an aliphatic hydrocarbon radical containing at least5 carbon atoms and R and R are lower alkyl radicals.

Filaments composed of acrylonitrile polymers are produced commerciallyeither by the dry spinning method or by the wet spinning method. In thelatter method and with which the present invention is concerned, thepoly mer is first dissolved in a suitable solvent. The resultingsolution of polymer is extruded through a spinneret submerged in asolution capable of coagulating the polymer. The spinneret is providedwith orifices, the diameter and number of which depend on the ultimatefilament denier and the number of filaments produced. During theirpassage through the spin bath, the filaments may be given a stretch todiminish the diameter thereof. This stretch is called the spinning orjet stretch.

In many respects the coagulation of acrylonitrile polymer solutions isthe most important step in the wet spinning process, for whateverstructure that is established in the filaments during coagulation canonly be modified during further processing into finished filaments.Initial Weaknesses or in homogeneities established during coagulationfrequently persist as faults in the final product. Consequently, thecomposition of the spin bath influences considerably the mechanicalproperties and appearance of the ultimate filaments.

Ordinarily, in a wet spinning operation, coagulation is accomplished byextruding the polymer solution into an aqueous bath sometimes containinga percentage of solvent or dissolved salt. As used herein an aqueous orwater bath refers to a composition having water as one of its majorcomponents. During coagulation there is an inward diffusion of bathliquid into the coagulating filaments and a corresponding outwardmovement of solvent into the spin bath. By employing a normal aqueousbath composition, the solvent and bath liquid interchange in such amanner that the resulting filament may contain voids along its lengthand may have a coarse, sponge-like structure that can be clearly seenwith an optical phase microscope. Filaments containing these voids orunfilled spaces do not possess the requisite physical properties desiredfor some end uses. For example, such filaments may exhibit lowertenacity and lower abrasion resistance than filaments not containingvoids.

To collapse the voids the filaments, during the aftertreatment thereof,are given a high degree of stretch and then dried at a rather hightemperature under tension thereby forming a more dense, collapsedfilamentary structure. Even by being subjected to this stretching anddrying operation, filaments produced from acrylonitrile so that they arewashed 3,402,235 Patented Sept. 17, 1968 polymers by the wet spinningprocess have a tendency to splinter or fibrillate and hence have a lowabrasion resistance. Fibrillation is a phenomenon characterized by thesplitting off from the parent filament or fiber of longitudinal sectionsof materials which are referred to as fibrils. The dimensions of thefibrils are small compared to those of the original filament or fiber.The aforesaid tendency to fibrillate may be attributed to void formationformed originally in the coagulating process. The abrasion resistance ofthe filaments may however be raised by subjecting them further to anannealing operation in which a series of elevated and reduced pressuretreatments are applied to the filaments. More specifically, annealingconsists of placing the acrylonitrile polymer filaments in a closedchamber, subjecting them to a high temperature and pressure in thepresence of wet steam and then evacuating the chamber. This treatingcycle is repeated as many times as needed. It will be appreciated thatthis annealing operation as just described is expensive and timeconsuming.

It is an object of this invention to provide a new and useful method ofwet spinning acrylonitrile polymer filaments having improved physicalproperties, particularly in regard to tenacity, elongation, and thelike, without the fibers having to be annealed.

It is another object of this invention to provide a new and usefulmethod of wet spinning acrylonitrile polymer filaments that possesselongation and essentially void free construction and therefore highabrasion resistance without the need of subjecting the filaments to anannealing operation.

It is another object of this invention to provide a new and usefulmethod of wet spinning acrylonitrile polymer filaments that possessexcellent basic dye acceptance.

It is still another object of the present invention to provide a newspin bath composition useful in the production of acrylonitrile polymerfilaments having improved physical properties.

Other objects and advantages of the invention will be come apparent fromthe following detailed description thereof.

In general, the objects of the present invention are accomplished byextruding an acrylonitrile polymer containing solution into a spin bathwhich comprises at least 50 percent by weight of a high molecular weightN,N-dialkylamide or mixtures of said amides. The spin bath may becomposed entirely of high molecular weight amide or it may contain, inaddition to the amide, up to 50 percent by weight ofN,N-dimethylacetamide and/or up to 50 percent by weight of water,depending on the miscibility of the amides with water.

Filaments so spun have high tenacity, high elongation, and betterabrasion resistance without the necessity of annealing than comparablefilaments spun in a watersolvent spin bath. It has been found that thehigh molecular weight N,N-dialkylamide bath extracts a higher percentageof initial solvent from the yarn than does a water spin bath and yieldsa denser, more collapsed yarn at the point the filaments are withdrawnfrom the spin bath. The bath can be used at temperatures of up to C. andpermits jet stretches of up to 2.0 times. After withdrawal from the spinbath the filaments of the present invention are washed with hot water toremove residual solvent and given an afterstretch to orient the polymermolecules. The afterstretching of the filaments can be accomplished byany suitable means which will effect the necessary extension, and it canbe accomplished by passing the filaments between two driven threadadvancing devices rotating at different predetermined peripheral speeds.The filaments during their passage between said devices are preferablypassed through a hot water bath and stretched simultaneously. It

is noted that the conditions of the water bath where stretching isaccomplished may be regulated so that it is possible to impart anafterstretch to the filaments to the extent of 8.0 times or more.Alternatively, the filaments may be dried prior to stretching andsubsequently given a substantial stretch in either steam or dry heat.

To further understand the invention, reference will be made to theattached drawings that form part of the present application.

In the drawings,

FIGURE 1 is a photomicrograph at a magnification of about 820 times of across section of acrylonitrile polymer filaments that were spun into acoagulation bath comprised of about 55 percent of dimethylacetamide andabout 45 percent of water and then dried and collapsed. FIGURE 2 is aphotomicrograph at a magnification of about 410 times of a longitudinalview of the same acrylonitrile polymer filament.

FIGURE 3 is a photomicrograph at a magnification of about 820 times of across section of acrylonitrile polymer filaments that were spun into acoagulation bath comprised of about 95 percent ofN,N,-dimethylmyristamide, about 3 percent of N,N-dimethylpalmitamide,and about 2 percent of N,N-dimethyllauramide and then dried andcollapsed. FIGURE 4 is a photomicrograph at a magnification of about 410times of a longitudinal view of the same acrylonitrile polymer filament.

FIGURE 5 is a photomicrograph at a magnification of about 820 times of across section of acrylonitrile polymer filaments that were spun into acoagulation bath comprised of about 85 percent of the amide mixturedescribed above and about percent of dimethylacetamide and then driedand collapsed. FIGURE 6 is a photomicrograph at a magnification of about410 times of a longitudinal view of the same acrylonitrile polymerfilament.

FIGURE 7 is a photomicrograph at a magnification of about 820 times of across section of acrylonitrile polymer filaments that were spun into acoagulation bath comprised of about 72.5 percent of the amide mixturedescribed above, about 15 percent of dimethylacetamide, and about 12.5percent of water, and then dried and collapsed. FIGURE 8 is aphotomicrograph at a magnification of about 410 times of a longitudinalview of the same acrylonitrile polymer filament.

It may be seen from FIGURES 1 and 2 that filament spun using aconventional coagulation bath contain undesirable voids whereas thefilaments spun using coagulation baths of this invention (FIGURES 3through 8) produce filament substantially free of undesirable voids.

Filaments produced according to the present invention pick up less waterin the washing step, consequently carrying less water with them to thedryers, and therefore can be dried more rapidly or at lower temperaturesthan ordinary wet spun filaments, provided the excess coagulatingN,N-dimethylamides are stripped from the filaments prior to the dryingstep.

In addition, the filaments show less tendency to fibrillate and can beused for textile purposes omitting the aforesaid annealing operation.Filaments may be spun which have a mirror smooth surface which is freefrom the pronounced crenulations which characterize normal wet spunfilaments. Moreover, the filaments have a soft silky hand or feel evenwithout a finish normally applied thereto.

Although it is not fully understood how the spin bath contributes to theformation of the improved fiber structure, it is believed that a rapidefflux of solvent out of as compared to bath inflow into a coagulatingfilament minimizes the formation of the aforedescribed porous structure.A denser and more compact filament is therefore attained.

The solutions to be spun in the spin bath composition of the presentinvention may be prepared by dissolving the acrylonitrile polymer inorganic solvents conventionally used in the art. Suitable solventsinclude, for example,

N,N dimethylformamide; N,N dimethylacetamide; ethylene carbonate;dimethyl sulfoxide; tetramethylene sulfone; nitromethane and water; tris(dimethylamido) phosphate; N-nitropiperidine; mixtures of ethylenesulfite with N,N-dimethylacetamide, N,N-dimethylformamide, andnitromethane and water; tri(betacyanoethyl) nitromethane;trichloronitropropanol; dimethyl methane phosphonate;gamma-butyrolactone; and the like and give solutions of acrylonitrilepolymer of high molecular weight without substantial modification byagitation at room temperature. It will be appreciated that a solutioncontaining a higher percentage of acrylonitrile polymer may be preparedby using higher temperatures. The concentration of the acrylonitrilepolymer varies with the particular solvent employed and for a givensolvent varies inversely with the molecular weight of the polymer. Informing the solution, the polymer is best employed in the form of a drypowder and the solution or spinning dope may be made by combining thepowder with the requisite quantity of solvent in a mixing device,preferably provided with means for controlling the temperature. The timerequired for mixing to obtain a useful solution is adjusted according tothe ease of dissolution. The resulting dope is usually a clear, viscousliquid. Ordinarily, for spinning purposes, a solution containing atleast 10 percent acrylonitrile polymer is desirable.

By acrylonitrile polymer used to define a polymer applicable to thepresent invention is meant polyacrylonitrile, copolymers and terpolymersof acrylonitrile, and blends of polyacrylonitrile and copolymers ofacrylonitrile with other polymerizable mono-olefinic materials. Ingeneral, a polymer of monomeric mixture of which acrylonitrile is atleast 50 percent by weight of the polymerizable content is useful in thepractice of the present invention. Besides polyacrylonitrile, usefulcopolymers are those of 50 or more percent of acrylonitrile and one ormore percent of other mono-olefinic monomers. Suitable other monomersinclude vinyl acetate and other vinyl esters of monocarboxylic acids,vinylidene chloride, vinyl chloride and other vinyl halides, dimethylfumarate and other dialkyl esters of fumaric acid, dimethyl maleate andother dialkyl esters of maleic acid, methyl acrylate and other alkylesters of acrylic acid, styrene and other vinyl substituted aromatichydrocarbons, methyl methacrylate and other alkyl esters of methacrylicacid, meth acrylonitrile, alpha-vinylpyridine and othervinyl-substituted heterocyclic nitrogen ring compounds, such as thevinyl imidazoles, etc., the alkyl-substituted vinylpyridines, vinylchloroacetate, allyl chloroacetate, methallyl chloroacetate, allylglycidyl ether, methallyl glycidyl ether, allyl glycidyl phthalate, andthe corresponding esters of other aliphatic and aromatic dicarboxylicacids, glycidyl acrylate, glycidyl methacrylate and other mono-olefinicmonomers copolymerizable with acrylonitrile.

Many of the more readily available monomers for polymerization withacrylonitrile, form copolymers which are not reactive with the dyestuffsand may therefore be impossible or difiicult to dye by conventionaltechniques. Accordingly, these non-dyeable fiber-forming copolymers maybe blended with polymers or copolymers which are in themselves moredye-receptive by reason of their physical structure or by reason of thepresence of functional groups which are chemically reactive with thedyestuff, whereby the dyestutf is permanently bonded to the polymer in amanner which lends resistance to the usual laundering and dry cleaningprocedures. Suitable blending polymers may be polyvinylpyridine,polyvinylpyrolidone, polymers of alkyl-substituted vinylpyridine,polymers of other vinyl-substituted N-heterocyclic compounds, thecopolymers of the various vinyl-substituted N-heterocyclic compounds andother copolymerizable monomers, particularly acrylonitrile.

Of particular utility are the blends formed of polyacrylonitrile or acopolymer of more than percent acrylonitrile and up to 10 percent ofvinyl acetate, and a copolymer of vinylpyridine or an alkyl-substitutedvinylpyridine and acrylonitrile, the said acrylonitrile being present insubstantial proportions, for example, 50 to 80 percent to provide heatand solvent resistance, and a substantial proportion of thevinylpyridine or derivative thereof to render the blend receptive toacid dyestuffs. Of particular utility are the blends of copolymers of 90to 98 percent acrylonitrile and 2 to percent vinyl acetate andsufficient copolymer of 10 to 70 percent acrylonitrile and 30 to 90percent vinylpyridine to produce a blended composition with a total of 3to 8 percent by weight of vinylpyridine.

The acrylonitrile polymer preferably possesses a molecular weight of atleast 10,000 and preferably between about 25,000 and 150,000, or evenhigher. This corresponds to a specific viscosity within the range of 0.1to 0.4. The specific viscosity value, as employed herein, is representedby the formula N time of flow of polymer solutions in seeonds time offiow of the solvent in seconds Viscosity determinations of the polymersolutions and solvent are made by allowing said solutions to flow bygravity at 25 C. through a capillary viscosity tube. In thedeterminations, a polymer solution containing 0.1 gram of the polymerdissolved in 100 ml. of N,N-dimethylformamide is employed. The mosteffective polymers for the preparation of filaments are those of uniformphysical and chemical properties and of relatively high molecularweight.

The polymers just described may be prepared by any conventionalpolymerization procedure, such as mass polymerization methods, solutionpolymerizatiommethods, or aqueous emulsion methods. The polymerizat onis normally catalyzed by known catalysts and is carried out in equipmentgenerally used in the art. However, the preferred practice utilizessuspension polymerization wherein the polymer is prepared in finelydivided form for immediate use in the filament forming operations. Thepreferred suspension polymerization involves batch procedures, whereinmonomers are charged with an aqueous medium containing the necessarycatalyst and dispersing agents. A more desirable method involves thesemi-continuous procedure in which the polymerization reactor containingthe aqueous medium is charged with the desired monomers graduallythroughout the course of the reaction. Entirely continuous methodsinvolving the gradual addition of monomers and the continuous withdrawalof polymer can also be employed.

The polymerization is catalyzed by means of a watersoluble peroxycompound, for example, the potassium, ammonium and other Water-solublesalts of peroxy acids, sodium peroxide, hydrogen peroxide, sodiumperborate, the sodium salts of other peroxy acids, and otherwatersoluble compounds containing the peroxy group. A wlde variation inquantity of peroxy compound is possible. For example, from 0.1 to 3.0percent by weight of the polymerizable monomer may be used. Theso-called redox catalyst system also may be used. Redox agents aregenerally compounds in a lower valent state which readily oxidized tothe higher valent state under the conditions of reaction. Through theuse of this reduction-oxidation system, it is possible to obtainpolymerization to a substantial extent at lower temperatures thanotherwise would be required, Suitable redox agents are sulfur dioxide,the alkali metal and ammonium bisulfites, and sodium formaldehydesulfoxylate. The catalyst may be charged at the outset of the reaction,or it may be added continuously or in increments throughout the reactionfor the purpose of maintaining a more uniform concentration of catalystin the reaction mass. The latter method is preferred because it tends tomake the resultant polymer more uniform in regard to its chemical andphysical properties.

Although the uniform distribution of the reactants throughout thereaction mass can be achieved by a vigorous agitation, it is generallydesirable to promote the uniform distribution of reagents by using inertwetting agents, or emulsion stabilizers. Suitable reagents for thispurpose are the water-soluble salts of fatty acids, such as sodiumoleate and potassium stearate, mixtures of Water-soluble fatty acidsalts, such as common soaps prepared by the saponification of animal andvegetable oils, the amino soaps, such as salts of triethanolamine anddodecylmethylamine, salts of rosin acids and mixtures thereof, thewater-soluble salts of half esters of sulfonic acids and long chainaliphatic alcohols, sulfonated hydrocarbons, such as alkyl arylsulfonates and any other of a wide variety of Wetting agents, which arein general organic compounds containing both hydrophobic and hydrophilicradicals. The quantity of emulsifying agent will depend upon theparticular agent selected, the ratio of the monomer to be used and theconditions of polymerization. In general, however, from 0.1 to 1.0weight percent based on the weight of the monomers can be employed,

The emulsion polymerizations are preferably conducted in glass orglass-lined vessels provided with means for agitating the contentstherein. Generally, rotary stirring devices are the most effective meansfor insuring the intimate contact of the reagents, but other methods maybe successfully employed, for example, by rocking or rotating thereactors. The polymerization equipment generally used is conventional inthe art and the adaptation of a particular type of apparatus to thereaction contemplated is within the providence of one skilled in theart.

The optimum methods of polymerization for preparing fiber-formingacrylonitrile polymers involve the use of polymerization regulators toprevent the formation of polymer units of excessive molecular weight.Suitable re ulators are the alkyl and aryl mercaptans, carbontetrachloride, chloroform, dithioglycidol and alcohols. The regulatorsmay be used in amounts varying from 0.001 to 2 percent, based on theweight of the monomer to be polymerized.

As pointed out above, the improvement herein is obtained by spinning thepolymer solution into a bath comprising at least 50 percent by weight ofa high molecular N,N-dia'lkylamide. These high molecular Weightdialkylamides are amides having the formula R I I-R2 wherein R is analiphatic hydrocarbon radical containing at least 5 carbon atoms and Rand R are lower alkyl radicals of up to 6 carbon atoms. Preferably, theamide will contain from 11 to 21 carbon atoms and R and R will be methylradicals.

Illustrative of suitable saturated amides that may be used in thepreparation of the compositions of this invention areN,N-dimethylcaprylamide, N,N-diethylcaprylamide, N,N-dimethylcapramide,N,N dimethylcaproamide, N,N-dimethyllauramide, N,N-dibutyllauramide,N,N-dimethylmyristamide, N methyl N-ethylmyristamide,N,N-dimethylpa1mitamide, N,N-dipropylheptadecamide,N,N-dimethylstearamide, N-methyl-N-ethyldocosamide, and the like.Illustrative of suitable unsaturated amides that may be used in thepreparation of the compositions of this invention areN,N-dimethylpalmitoleamide, N,N-di methyloleamide, N,N-dibutyloleamide,N, N-dimethyllinoleamide, N,Ndiethyllinoleamide,N-methyl-N-ebutylpropyllinoleamide, N,N-dirnethyllinolenamide, and thelike. Mixtures of the used. These compounds may be prepared by reactingan acid anhydride with [a dialkyl amine such as dimethyl amine.

The spin bath will comprise at least 50 percent of high molecular weightpolyamide. Preferably, the spin bath will be composed of from about 70to percent by weight of a high molecular weight polyamide, from aboutabove amides may also be to 30 percent by weight of a solvent for theacrylonitrile polymer selected from the solvents disclosed above,preferably N,N-dimethy1acetamide, and from about 0 to 30 percent byweight of water. Although wide variations in the spin bath temperaturesare permitted, it is preferred that the temperature be of the order ofabout 20 C. to 100 C.

During spinning the solvent concentration will build up in the spinbath. Fresh spin bath composition should be supplied to the spin bathwhen the solvent concentration therein becomes excessively high, withthe spent composition being recovered by conventional methods. Up to 50percent by weight of solvent may ordinarily be tolerated in the spinbath without adversely effecting the filament appearance or properties.The amount of solvent that can be tolerated is determined by theparticular amide or amides used.

Additives such as delusterants, antioxidants, plasticizers, coloringpigments, stabilizers, and other like modifying agents may beincorporated in the polymer solution without departing from the scope ofthe present invention.

Although reference has been made herein mainly to the production offilaments from the acrylonitrile polymers, the process of this inventionis generally applicable to the production of any shaped article frompolymers of acrylonitrile such as fibers, filaments, bristles, tubings,films, pellicles, and the like.

The following examples in which parts and percentages are given byweight unless otherwise specified illustrate preferred methods ofpreparing solutions in accordance with the principles of this inventionand of employing the spin bath composition in the manufacture ofcommercially satisfactory filaments. The invention is not to be limitedby the details set forth in the examples.

The basic dye acceptance values given in the examples were obtained bydyeing the fiber at about 97 C. for 2 hours in a dye bath containing 20percent by weight of Sevron Blue 26 dye (C.=I. Basic Blue 22). Theexhausted dyebath was then analyzed spectrophotometrically to determinethe amount of dye remaining and the percentage of dye uptake on thefiber.

The test for color stability used in the examples consists of ameasurement of purity and brightness as calculated from the tristimulusvalues determined on a GE spectrophotometer by the methods recommendedby the Standard Observer and Coordinate System of the InternationalCommission on Illumination, as fully set forth in the Handbook ofColorimetry, published by the Technology Press, Massachusetts Instituteof Technology, in 1936.

The results given in the examples for dyelightfastness represent thedegree of alteration of shade of the exposed fibers after an exposure of80 standard Fade-O-meter hours (SFH) and were determined on a subjectivevisual scale as follows:

5 Negligible or no change. 4 Slightly changed.

3 Noticeably changed.

2 Considerably changed.

1 Markedly changed.

Light Sample maintains color shade but loses depth. White Sample colorshade and depth lighten or change toward white.

Example 1 fibers were then annealed in saturated steam at 35 p.s.i.g.The annealed fiber was found to have a tenacity of 2.3 grams per denier,an elongation of 29 percent, and a basic dye acceptance of 5.5 percent.The dyed fibers were exposed for a total of standard hours in thefade-O- meter and the dyed light stability found to be 3.0 Light. Theannealed undyed fiber was evaluated for color on the GEspectrophotometer and found to have a purity of 5 .9 units and abrightness of 84.5 units.

Example 2 A spinning dope composed of about 93 percent acrylonitrile andabout 7 percent of vinyl acetate dissolved in a solvent comprisingdimethylacetamide was wet spun according to conventional techniquesusing a coagulation bath comprised of 100 percent of an amide mixturecomprising about 95 percent of N,N-dimethyllauramide, about 3 percent ofN,N-dimethylmyristamide, and about 2 percent of N,N-dimethylcapramide toproduce fiber. The fiber produced was found to have a tenacity of 2.7grams per denier and an elongation of 35 percent. The fiber wasevaluated for color on the GE spectrophotometer and found to have apurity of 5.9 units and a brightness of 87.0 units. The fibers were thendyed with basic dyes and their basic dye acceptance determined to be 7.6percent. These dyed fibers were exposed for a total of 80 standard hoursin the fade-O-meter and the dyed light stability found to be 3.5 Light.The fibers were then annealed in saturated steam at 35 p.s.i.g. Theannealed fibers were found to have an elongation of 52 percent.

Example 3 A spinning dope composed of about 93 percent of acrylonitrileand about 7 percent of vinyl acetate dissolved in a solvent comprisingdimethylacetamide was wet spun according to conventional techniquesusing a coagulation bath comprising about 85 percent of the amidemixture of Example 2 and about 15 percent of dimethylacetamide toproduce fiber. These fibers were found to have a tenacity of 2.8 gramsper denier and an elongation of 30 percent. The fiber was evaluated forcolor on the GE spectrophotometer and found to have a purity of 5.9units and a brightness of 87.4 units. The basic dye acceptance of thefiber was determined to be 8.2 percent. The fiber had a dyed lightstability rating of 3.0 Light after 80 hours exposure in thefade-O-meter. The fibers were then annealed in saturated steam at 35p.s.i.g. The annealed fiber was found to have an elongation of 54percent.

Example 4 A spinning dope composed of about 93 percent of acrylonitrileand about 7 percent of vinyl acetate dissolved in a solvent comprisingdimethylacetamide was wet spun according to conventional techniquesusing a coagulation bath comprised of percent of an amide mixturecomprising about 50 percent of N,N-dimethylcaprylamide, about 40 percentof N,N-dirnethylcapramide, about 5 percent of N,N-dimethyllauramide, andabout 5 percent of N,N-dimethylcaproamide to produce fiber. These fiberswere found to have a tenacity of 1.7 grams per denier and an elongationof 36 percent. The fiber was evaluated for color on the GEspectrophotometer and the purity found to be 4.4 units and thebrightness 89.6 units. The fibers were then dyed with basic dyes and thebasic dye acceptance determined to be 8.0 percent. The dyed fibers wereexposed for 80 standard hours and the fade-O-meter and the dyed lightstability determined to be 3.5 Light. The fibers were annealed insaturated steam at 35 p.s.i.g. The annealed fibers were found to have anelongation of 69 percent.

Example 5 A spinning dope composed of about 93 percent of acrylonitrileand about 7 percent of vinyl acetate dissolved in a solvent comprisingdimethylacetamide was wet spun according to conventional techniquesusing a coagulating bath comprised of 100 percent of an amide mixturecomprising about 95 percent of N,N-dimethylmyristamide, about 3 percentof N,Nrdimethylpalmitamide, and about 2 percent of N,N-dimethyllauramideto produce fiber. These fibers were found to have a tenacity of 3.5grams per denier and an elongation of 33 percent. The fiber wasevaluated for color on the GE spectrophotometer and the purity found tobe 7.0 units and the brightness 84.8 units. The fibers were then dyedand the basic dye acceptance determined to be 6.2.percent. The. dyedfibers were exposed for 80 standard hours in the fade-O- meter and thedyed light stability determined to be 3.5 White. The fibers wereannealed in saturated steam at 35 p.s.i.g. The annealed fibers werefound to have an elongation of 46 percent.

Example 6 Avspinning dope composed of about 93 percent of acrylonitrileand about 7 percent of vinylacetate was wet spun according toconventional techniques using a coagulation bath comprised of about 12.5percent of dimethylacetamide, about 15 percent of water, and about 72.5percent of the amide mixture of Example 5 to produce fiber. These fiberswere found to have a tenacity of 2.0 grams per denier and an elongationof 27 percent. The fibers were evaluated for col-or on the GEspectrophotometer and the purity found to be 7.0 units and thebrightness 85.4 units.The fibers were then dyed with basic dyes and thebasic dye acceptance determined to be 6.7 percent. The dyed fibers wereexposed for 80 standard hours in the fade-O-meter and the dyed lightstability determined to be 3.0 White. The fibers were annealed insaturated steam at 35 p.s.i.g. The annealed fibers were found to have anelongation of 45 percent.

As many variations within the spirit and scope of this invention willoccur to those skilled in the art, it is to be understood that theinvention is not limited to the specific embodiments thereof except asset forth in the appended claims.

What is claimed is:

1. A process for wet spinning of shaped objects of an acrylonitrilepolymer containing at least 50 percent by,

weight polymerized acrylonitrile which comprises extruding a solution ofsaid polymer into a spin bath comprising at least 50 percent by weightof an amide selected from the group consisting of amides having theformula.

R1 R-i-lL-Rz wherein R is an aliphatic hydrocarbon radical containing atleast carbon atoms and R and R are lower alkyl radicals and mixtures ofsaid amides.

2. A process for wet spinning of shaped objects of an acrylonitrilepolymer containing at least 50 percent by weight polymerizedacrylonitrile and at most 50 percent by weight of another mono-olefinicmonomer copolymerized therein which comprises extruding a solution ofsaid polymer into a spin bath comprising at least 50 percent by weightof an amide selected from the group consisting of amides having theformula 0 R1 R-(IJI-I1IR2 wherein R is an aliphatic hydrocarbon radicalcontaining at least 5 carbon atoms and R and R are lower alkyl radicalsand mixtures of said amides, up to about 50 percent by weight ofN,N-dimethylacetamide and up to about 50 percent by weight of water.

3. A process for wet spinning of shaped objects of acrylonitrile polymercontaining at least 50 percent by weight of polymerized acrylonitrileand at most 50 percent by weight of another mono-olefinic monomercopolymerized therewith which comprises extruding a solu tion of saidpolymer into a spin bath comprising from about 70 to about 100 percentby weight of an amide 10 selected from the group consisting of amideshaving the formula 2 r R-( J-N-R,

wherein R is an aliphatic hydrocarbon radical containing from about 11to 21 carbon atoms and R and R are methyl groups and mixtures of saidamides, from about 0 to 30 percent by weight of N,N-dimethylacetamideand from about 0 to 30 percent by weight of water and maintained at atemperature of 20 to C.

4. The process as defined in claim 3 wherein the spin bath consistsessentially of an amide selected from the group consisting of amideshaving the formula wherein R is an aliphatic hydrocarbon radicalcontaining from about 11 to 21 carbon atoms and R and R are methylgroups and mixtures of said amides.

5. A process for wet spinning of shaped objects of an acrylonitrilepolymer containing at least 50 percent by weight polymerizedacrylonitrile which comprises extruding a solution of said polymerthrough a shaped orifice submerged in a spin bath comprising at least 50percent by weight of an amide selected from the group consisting ofamides having the formula OR "I RON-Rz wherein R is an aliphatichydrocarbon radical containing at least 5 carbon atoms and R and R arelower alkyl radicals and mixtures of said amides.

6. A process for wet spinning of shaped objects of an acrylonitrilepolymer containing at least 50 percent by weight polymerizedacrylonitrile and at most 50 percent by weight of another mono-olefinicmonomer copolymerized therewith which comprises extruding a solution ofsaid polymer through a shaped orifice submerged in a spin bathcomprising at least 50 percent by weight of an amide selected from thegroup consisting of amides having the formula wherein R is an aliphtichydrocarbon radical containing at least 5 carbon atoms and R and R arelower alkyl radicals and mixtures of said amides, up to about 50 percentby weight of N,N-dimethylacetamide, and up to about 50 percent by weightof water.

7. A process for wet spinning of shaped objects of an acrylonitrilepolymer containing at least 50 percent by weight polymerizedacrylonitrile and at most 50 percent by weight of another mono-olefinicmonomer copolymerized therewith which comprises extruding a solution ofsaid polymer through a shaped orifice submerged in a spin bath composedof from about 70 to 100 percent by weight of an amide selected from thegroup consisting of amides having the formula wherein R is an aliphatichydrocarbon radical containing from about 11 to 21 carbon atoms and Rand R are methyl groups and mixtures of said amides, from about 0 to 30percent by weight of N,N-dimethylacetamide, and from about 0 to 30percent by weight of water, said spin bath being maintained at atemperature of 20 to 100 C. 8. The process as defined in claim 7 whereinthe spin bath consists essentially of an amide selected from the groupconsisting of amides having the formula wherein R is an aliphatichydrocarbon radical containing from about 11 to 21 carbon atoms and Rand R are methyl groups and mixtures of said amides.

9. A process for wet spinning of filaments of an acrylonitrile polymercontaining at least 50 percent by weight polymerized acrylonitrile whichcomprises extruding a solution of said polymer through a shaped orificesubmerged in a spin bath comprising at least 50 percent by weight of anamide selected from the group consisting of amides having the formulaIll wherein R is an aliphatic hydrocarbon radical containing at least 5carbon atoms and R and R are lower alkyl radicals and mixtures of saidamides, thereby precipitating said polymer from its solution into theform of a filament, withdrawing said filament from said spin bath,passing said filament through a boiling water bath wherein said filamentis given a substantial stretch, and drying said filament, whereby adense filament having a smooth surface substantially free fromcrenulations is .formed.

10. A process for wet spinning of filaments of acrylonitrile polymercontaining at least 50 percent by weight acrylonitrile and at most 50percent by weight of another mono-olefinic monomer copolymerizedtherewith, which comprises extruding a solution of said polymer througha shaped orifice submerged in a spin bath comprising at least 50 percentof an amide selected from the group consisting of amides having theformula wherein R is an aliphatic hydrocarbon radical containing atleast 5 carbon atoms and R and R are lower alkyl radicals and mixturesof said amides, up to 50 percent by weight of N,N-dimethylacetamide andup to 50 percent by weight of water, thereby precipitating said polymerfrom its solution into the form of a filament, withdrawing said filamentfrom said spin bath, passing said filament through a boiling water bathwherein said filament is given a substantial stretch, and drying saidfilament, whereby a dense filament having a smooth surface substantiallyfree from crenulations is formed.

11. A process for wet spinning of filaments of acrylonitrile polymercontaining at least percent by weight acrylonitrile and at most 50percent by weight of another mono-olefinic monomer copolymerizedtherewith, which comprises extruding a solution of said polymer througha shaped orifice submerged in a spin bath consisting of from about topercent by weight of an amide selected from the group consisting ofamides having the formula wherein R is an aliphatic hydrocarbon radicalcontaining from about 11 to 21 carbon atoms and R and R are methylgroups and mixtures of said amides, from about 0 to 30 percent by weightof N,N-dimethylacetamide and from about 0 to 30 percent by weight ofwater and maintained at a temperature of 20 to 100 0., therebyprecipitating said polymer from its solution into the form of afilament, withdrawing said filament from said spin bath, passing saidfilament through a boiling water bath wherein said filament is given asubstantial stretch, and drying said filament, whereby a dense filamenthaving a smooth surface substantially free from crenulations is formed.

12. The process as defined in claim 11 wherein the spin bath consistsessentially of an amide selected from the group consisting of amideshaving the-formula from about 11 to 21 carbon atoms and R and R aremethyl groups and mixtures of said amides.

References Cited UNITED STATES PATENTS 2,728,631 12/1955 Drisch et al.18-54 JAMES A. SEIDLECK, Primary Examiner.

H. H. MINTZ, Assistant Examiner.

